Warning signs (i.e., warning, hazard or caution signs) are frequently used to alert pedestrians to dangerous or harmful conditions such as a wet or slippery floor or wet paint. Typically, such signs are expendable sheet-like objects that are easy to hang and provide a clearly visible textual message. Because they are relatively inexpensive, a plurality of caution signs may be posted to cover a widespread area. While these devices are effective for warning attentive, literate passersby, they do not attract inattentive pedestrians or effectively communicate a warning message to illiterate or foreign-speaking passersby. Additionally, they are ineffective in darkened conditions (e.g., at nighttime or in a dark room).
Attempts have been made to integrate a sound emitting unit within the structure of certain signs. However, such devices have several shortcomings. They are not portable, programmable, stand alone modules that can be adapted and re-adapted to any signs. Instead, they tend to have components distributed throughout the structure of a sign. Additionally, the integrated units tend to be bulky, costly and inefficient. Consequently, such devices are not well suited for attachment to certain signs, particularly expendable sheet-like signs.
Another shortcoming of such prior devices is lack of reliability. Environmental changes tend to erroneously trigger such prior devices. Frequently, messages are played when no one is around to warn. To conserve battery power and ensure that messages are played when a passerby approaches, a more reliable device is needed.
As a consequence of the foregoing, there exists a longstanding need for a new and improved integrated audio module configured for attachment to conventional warning signs and adapted to reliably produce a programmed audible message upon detecting the presence of a passerby. The invention is directed to overcoming one or more of the problems as set forth above.